Effect of male mass trapping of Agriotes species on wireworm abundance and potato tuber damage

The use of sex pheromones as an option to control wireworms via mass trapping and the biology of Agriotes lineatus (L.) were investigated in a long-term field experiment at an organic research farm in North Rhine-Westphalia, Germany. Plots supplied with sex pheromone traps were compared with untreated control plots. Over 5 years, a total of 12,378 male adults of A. lineatus, Agriotes obscurus (L.) and Agriotes sputator (L.) were captured in six traps located at 40 m distance in a grass-clover ley. The swarming period of the males lasted from late April to late August with one major and a small peak in the successive years for all three species. During 2006 and 2008 A. lineatus was the dominant species trapped with 4,005 male adults followed by A. obscurus (3,045) and A. sputator (1,213). The total number of wireworms captured over all sampling dates only slightly differed between the two pheromone treated plots (201 individuals) and the two control plots (230 individuals) suggesting no effect of mass trapping on wireworm abundance. The peak oviposition period of A. lineatus lasted from May to early June. Over a 30 month period the larvae passed through 8 instar stages (life cycle not completed) and attaining L4 instar stage before the first and L8 before the second overwintering. Non-chemical wireworm control will have to focus on cultural approaches including soil tillage and rotation design taking data on biology into account.